Hierarchical magnetic nanoparticle-enzyme mesoporous assemblies embedded in macroporous scaffolds

Abstract

A hierarchical catalyst composition comprising a continuous or particulate macroporous scaffold in which is incorporated mesoporous aggregates of magnetic nanoparticles, wherein an enzyme is embedded in mesopores of the mesoporous aggregates of magnetic nanoparticles. Methods for synthesizing the hierarchical catalyst composition are also described. Also described are processes that use the recoverable hierarchical catalyst composition for depolymerizing lignin, remediation of water contaminated with aromatic substances, polymerizing monomers by a free-radical mechanism, epoxidation of alkenes, halogenation of phenols, inhibiting growth and function of microorganisms in a solution, and carbon dioxide conversion to methanol. Further described are methods for increasing the space time yield and / or total turnover number of a liquid-phase chemical reaction that includes magnetic particles to facilitate the chemical reaction, the method comprising subjecting the chemical reaction to a plurality of magnetic fields of selected magnetic strength, relative position in the chemical reaction, and relative motion.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Application No. 61 / 710,110, filed Oct. 5, 2012, and U.S. Provisional Application No. 61 / 767,477, filed Feb. 21, 2013, both of which are herein incorporated by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]This invention was made with government support under contract to the Northeast Sun Grant Initiative at Cornell University US Department of Transportation Assistance #DTOS59-07-G-00052. The government has certain rights in the invention.BACKGROUND OF THE DISCLOSURE[0003]Peroxidases (EC 1.11.1) are widely found in biological systems and form a subset of oxidoreductases that reduce hydrogen peroxide (H2O2) to water in order to oxidize a large variety of aromatic compounds ranging from phenol to aromatic amines. The reaction cycle of peroxidases is quite complex and begins with activation of heme by H2O2 to form the two-electron activated Compound I (...

AI Technical Summary

Benefits of technology

[0005]It has been discovered herein that bionanocatalysts (BNCs) consisting of an enzyme, particularly a free-radical-producing (FRP) enzyme, such as horseradish peroxidase (HRP), self-assembled with magnetic nanoparticles (MNPs) possess an enhanced enzymatic activity. In particular, it has herein been found that the self-assembled clusters of enzyme and magnetic nanoparticles generally possess faster turnover and lower inhibition of the enzyme as compared with the free enzyme or the magnetic nanoparticle clusters without enzyme. It has herein furthermore been found that the size and magnetization of the MNPs affect the formation and ultimately the structure of the BNCs, all of which have a significant impact on the activity of the entrapped enzymes. Particularly by virtue of their surprising resilience under various reaction conditions, the BNCs described herein can he used as an improved enzymatic or catalytic agent where other such agents are currently used, and they can furthermore be used in other applications where an enzyme has not yet been considered or found applicable.

[0013]In still other aspects, the invention is directed to a method for increasing a space time yield and / or total turnover number of a liquid-phase chemical reaction that includes magnetic particles, such as any of the BNCs or hierarchical catalyst assemblies thereof, to facilitate the chemical reaction. In the method, the liquid-phase chemical reaction containing magnetic particles therein is subjected to a plurality of magnetic fields of selected magnetic strength, relative position in the liquid-phase chemical reaction, and relative motion to spatially confine the magnetic particles, wherein the magnetic strength, relative positioning, and relative motion of the plurality of magnetic fields are provided by a system of electromagnets in which current flow is appropriately controlled or adjusted.

[0014]By virtue of the larger size and the mass magnetization of the overall hierarchical assembly containing BNCs incorporated into the macroporous framework, the enzyme-containing BNCs can be more easily captured by an external magnetic field, and thus, more easily removed from a reaction medium. The simplified removal furthermore permits the more facile re-use of the catalysts. Another benefit of the hierarchical assembled catalysts described herein is that the larger size helps to preserve enzymatic activities. Moreover, BNCs attached onto the surface of magnetic microparticles are less prone to over-aggregation when subjected to magnetic fields that may be used to remove the BNCs or enhance the reaction.

Problems solved by technology

Therefore, the complex kinetics associated with peroxidase enzymes can restrict their use in many processes and bioprocesses.

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